The present invention relates to an ion prime mover or engine. Such engines or prime movers produce thrust by the utilization of the reaction drive principle. A so called reaction mass is ionized in an ionization chamber by electric energy and the positively charged ions are accelerated in an electrostatic field. The reaction or supporting mass is preferably mercury in the gaseous state. However, one of the rare gases may also be used, for example neon or xenon.
It is a special problem for the operation of an ion engine to produce the ions in an efficient manner. According to a known method for producing a plasma a high frequency electromagnetic alternating field is produced inside a chamber filled with the reaction or support mass. The ions produced in this manner are accelerated out of the ionization chamber by means of an electrostatic field which drives the ion through apertured electrodes. One ion engine of this type is known under the name "RIT" (Radiofrequency-Ion-Thruster). AIAA Paper No. 73-1146 describes such a "RIT" engine.
Investigations made in connection with one such ion engine have shown that the ion density available in the ionization chamber is too small in comparison to the energy required for producing the high frequency alternating field. In other words, the ionization is not efficient. Another drawback of the prior art device is seen in that at the rate thrust of the ion engine, extremely large current losses occur at the acceleration electrodes. Besides, the stable operation of the prior art ion engine is frequently disturbed by electrical arcing.